An efficient conversion of biorenewable ferulic acid into bio‐catechol has been developed. The transformation comprises two consecutive defunctionalizations of the substrate, that is, C−O (demethylation) and C−C (de‐2‐carboxyvinylation) bond cleavage, occurring in one step. The process only requires heating of ferulic acid with HCl (or H2SO4) as catalyst in pressurized hot water (250 °C, 50 bar N2). The versatility is shown on a variety of other (biorenewable) substrates yielding up to 84 % di‐ (catechol, resorcinol, hydroquinone) and trihydroxybenzenes (pyrogallol, hydroxyquinol), in most cases just requiring simple extraction as work‐up.
A green, efficient and cheap demethylation reaction of aromatic methyl ethers with mineral acid (HCl or H2SO4) as catalyst in high temperature pressurized water provided the corresponding aromatic alcohols (phenols,...
A new approach to synthesize valuable 3,4dialkoxyanilines and alkyl propionates from lignin-derived 4propylguaiacol and -catechol with overall isolated yields up to 65% has been described. The strategy is based on the introduction of nitrogen via a Beckmann rearrangement. Amino introduction therefore coincides with a C-defunctionalization reaction; overall a replacement of the propyl chain by an amino group is obtained. The process only requires cheap bulk chemicals as reagents/reactants and does not involve column chromatography to purify the reaction products. Furthermore, all carbon atoms from the biorenewable lignin-derived monomers are transformed into valuable compounds. Greenness was assessed by performing a Green Metrics analysis on two dialkoxyanilines. A comparison was made with literature routes for these compounds starting from a petrochemical substrate.
A catalytic route is developed to synthesize bio-renewable catechol from softwood-derived lignin-first monomers. This process concept consists of two steps: 1) O-demethylation of 4n-propylguaiacol (4-PG) over acidic beta zeolites in hot pressurized liquid water delivering 4-n-propylcatechol (4-PC); 2) gas-phase C-dealkylation of 4-PC providing catechol and propylene over acidic ZSM-5 zeolites in the presence of water. With large pore sized beta-19 zeolite as catalyst, 4-PC is formed with more than 93 % selectivity at nearly full conversion of 4-PG. The acid-catalyzed C-dealkylation over ZSM-5 zeolite with medium pore size gives a catechol yield of 75 %. Overall, around 70 % catechol yield is obtained from pure 4-PG, or 56 % when starting from crude 4-PG monomers obtained from softwood by lignin-first RCF biorefinery. The selective cleavage of functional groups from biobased platform molecules through a green and sustainable process highlights the potential to shift feedstock from fossil oil to biomass, providing drop ins for the chemicals industry.
An efficient conversion of biorenewable ferulic acid into bio-catechol has been developed. The transformation comprises two consecutive defunctionalizations of the substrate,t hat is,C ÀO( demethylation) and CÀC( de-2-carboxyvinylation) bond cleavage,occurring in one step.The process only requires heating of ferulic acid with HCl (or H 2 SO 4 )a s catalyst in pressurized hot water (250 8 8C, 50 bar N 2 ). The versatility is shown on av ariety of other (biorenewable) substrates yielding up to 84 %di-(catechol, resorcinol, hydroquinone) and trihydroxybenzenes (pyrogallol, hydroxyquinol), in most cases just requiring simple extraction as work-up.
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